Flame jet drilling



Nov. 4, 1969 ,J, A. BROWNING 3,476,194

FLAME JET DRILLING Filed April 29, 1968 'llll worli Ill/II I 1111/11/11 II IA 1 mill &2

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United States Patent 3,476,194 FLAME JET DRILLING James A. Browning, Hanover, N.H., assignor to Browning Engineering Corporation, a corporation of New Hampshire Filed Apr. 29, 1968, Ser. No. 733,727 Int. Cl. E21b 7/14, 7/18, 21/04 US. Cl. 175-14 6 Claims ABSTRACT OF THE DISCLOSURE My invention relates to improvements in devices for the flame drilling of rock, ores, and other mineral materials. More particularly, novel means are provided to permit the drilling of holes of smaller diameter than heretofore possible with this general t echnique.

In many cases, the drilling of holes in rocks and soils is concerned mainly with linear rates, the purpose being to produce holes of substantial depth in minimum time and at minimum cost. Hole diameters are of secondary consideration, as for example in the production of blast holes, or in drilling a series of closely spaced holes for removal of blocks of material.

The development of flame drilling has put this technique into general use; however with conventional methods (often referred to as flame jet piercing) an unnecessary volume of material is removed in producing a hole of given length. This is so because flame jet burners as presently constructed and used scour out a hole diameter substantially larger than the outside diameter of the burner itself. This is usually undesirable, and my invention permits the translation of more of the energy expended into linear progress of the hole being produced. At the same time, larger hole sections can be still produced where desired.

A better understanding of the invention may be obtained from the figures, where FIGURE 1 is a cross-sectional view of a flame drill in operation.

FIGURE 2 shows the burner of FIGURE 1 provided with apparatus of this invention.

FIGURE 3 shows alternate apparatus useful to the practice of the invention.

FIGURE 4 is still another embodiment of the invention.

In FIGURE 1 an internal burner 12 is drilling hole 14 in mineral mass 11. In this case the burner is provided with a flow compressed air (or other oxidizer) through tube 17 with oil (or other fuel) flowing through tube 18. Cooling water is supplied through tube 19 and this water then exhausts from the burner through tube 20 after circulating in the closed water jacket in the burner as well understood. The burner is supported by tube 16 which also serves to encase the service tubes 17 through 20.

A working jet flame 13 is directed against the bottom of the hole and the burner is lowered as the hole depth progresses. It is usually desirable that the flame velocity be supersonic and that the standoff distance of the burner face (from the hole bottom) be maintained at from 3 to 8 inches.

In prior devices it has been the practice to discharge the cooling water from near the end of the burner to 3,476,194 Patented Nov. 4, 1969 reduce the complexity of the apparatus, to assist in removing the cuttings from the hole, and to reduce the amount of dust exiting with the upward flow of gases and detritus 21. It should be emphasized that in these prior burner devices only the minimum flow of water (as required to provide adequate cooling of the burner) was used and discharged into the hole cavity. In all cases this flow was inadequate for the purposes of the present invention. Also, this water was injected in such fashion as to impinge against the hole bottom to help in the removal of fused material.

In the present invention water is used in a novel manner made to control the hole size. In FIGURE 1 the full hole size is not achieved until the burner has progressed well down the hole. For the position shown of burner 12 it is seen that the hole widens upward from the bottom reaching maximum size at 22. Where the largest possible hole size is desired, but where water is injected to control the effluent material, such water injection should be at a point where the water will contact the hole wall at a point above 22.

Where it is desired to produce a hole diameter smaller than that produced in the absence of water injection, water is injected at a location which will cause its impingement against the hole wall below the plane of point 22. This is shown in FIGURE 2 where the burner is provided with a ring of downward sloping water-injector holes 26. Water jets 27 impinge against the rock surface at 28 terminating any further cutting action of the hot flame gases. Different injector-hole location anld angle result in the water striking the hole at different distances above the hole bottom. Where, in the absence of this water quench, the hole diameter could he, say, 8 inches, by proper use 'of the quench water the hole can be made to be only slightly larger than the burner itself; i.e. 4 inches. The rock of the shaded region 29 would have been removed if it were not for the quench water.

Where the quench water is introduced through fixed holes (holes 26 of FIGURE 2) control of hole diameter may be effected by varying the water mass flow. A smaller flow of water, possessing less momentum, will strike the wall higher up the hole than in the case of larger water flows. This eifect is produced by the upward vector resulting from the hot gases. An alternative to varying the water flow rate is to provide the injection holes at different locations as illustrated in FIGURE 3. Here, a slidable collar 30 acts as a manifold and contains the water-injector holes 32. Water is provided through tube 31. The lower the position of collar 30, the smaller the hole diameter at a given water flow rate. The collar position may be varied by the operator as drilling progresses, as desired, by raising or lowering tube 31 relative to the burner body.

In FIGURE 4 the drill has passed through a crack 33 in the rock. Such a crack, or other discontinuity, by inhibiting spalling action may lead to a narrowing of the hole by formation of shoulder 34. When the crack is passed the shoulder 34 will remain. This is usually undesirable. By reducing the quench water flow at the proper time, increased heat may be applied against shoulder 34 to aid in its removal. One method of accomplishing this is by use of water cooled feelers" 35. In this case the feelers 35 are hinged at water collar 30. When they strike the narrowed wall they activate a valving mechanism which reduces the water flow within that region. An alternate technique is to sense the gas pressure near the end of the burner. A restriction caused by shoulder 34 produces an increase in the gas pressure. This pressure change is then used to control the water flow rate.

The controlled use of water in conjunction with flame drilling thus makes possible effective control of hole diameter, approaching as a lower limit the diameter of the burner unit. This technique is useful to produce a wide variety of special purpose holes used in the mineral, rock and soil processing industry.

Iclaim:

1. The method of regulating the hole size produced by the process of jet flame drilling in mineral masses with an internal burner, comprising directing a stream of coolant against the walls of the hole being drilled at a selected point above the point of application of the burner jet flame.

2. The method according to claim 1 in which said coolant is water.

3. The method according to claim 11 in which said stream is varied during drilling to produce hole sections of diifering diameters.

4. The method of obtaining the maximum hole size produced by the process of flame jet drilling in mineral masses With an internal burner, comprising introducing a coolant stream of liquid into said hole so as to impinge upon the hole walls at a point above that at which the hole has already reached maximum size in the absence of said coolant.

5. The improvement in an internal burner having a jet flame exit nozzle for jet flame drilling comprising; the addition of a coolant manifold circumferentially arranged around the body of said burner, the axial position References Cited UNITED STATES PATENTS Re. 22,964 1/1948 Burch 175-13 2,628,817 2/1953 Wyland 17514 2,675,993 4/1954 Smith et al. 175-13 X 2,693,937 11/1954- Wyland 175-14 2,738,162 3/1956 Aitchison 175--l4 2,882,016 4/1959 Aitchison 175-14 3,045,766 7/1962 Fleming l14 OTHER REFERENCES New Developments In Linde Jet Piercing, pub. January 1966, Linde Division of Union Carbide Corp, p. 10.

DAVID H. BROWN, Primary Examiner US. Cl. X.R. -13 

